Alternators don't produce knocking noises.

I would suggest checking the serpentine belt to see if it is worn. A worn belt or weak belt tension tends to produce knocking noises and noise would usually change in rythm when A/C is turne on or off.

They are concluding that the bearing is going bad and IF they are correct, the alternator will fail and lock up eventually.. I would get a second opinion. The alternator price is a bit steep too.

If the bearings are bad. they can be easily replaced at a much lower cost.

I don't think you will find anybody willing to take an alternator apart.

Guess we are living in different worlds, lol.

I don't doubt you would be capable but the general consensus of repair shops that I have been familiar with would not take that route and the parts stores would give you a "deer in the headlights" look if you asked for an alternator bearing..

Yup, I agree with that. Over here i would say 90 % of so called shops are nothing more than fitter shops where they would replace components and hope it solves problems if there are any.